Trimethylamine-(ethylcarbamoyl)borane, Me.sub.3 N.BH.sub.2 C(O)NHEt, is a precursor in the synthesis of Me.sub.3 N.BH.sub.2 COOH, the protonated boron analogue of the dipolar amino acid betaine .sup.+ Me.sub.3 NCH.sub.2 COO.sup.-. Both Me.sub.3 N.BH.sub.2 COOH and its ethylcarbamoyl derivative have demonstrated significant antitumor and antihyperlipidemic activity in mice. B. F. Spielvogel et al., Am. Chem. Soc., 93, p. 5702 (1976); I. H. Hall et al., J. Pharm. Sci., 68, p. 685 (1979) and I. H. Hall et al., J. Pharm. Sci., 70, p. 339 (1981). Also, the trimethylamine-(ethylcarbamoyl)borane showed significant antiinflammatory and antiarthritic activities in animal model studies. I. H. Hall et al., J. Pharm. Sci., 69, p. 1025 (1980) Because of their potential biological activities the preparation of the remaining amine members was undertaken. Related organoborane technology is disclosed in U.S. Pat. No. 4,209,510; No. 4,312,980 and No. 4,368,194.